1. Field of the Invention
Exemplary embodiments of the present invention relates to a light emitting device and a method of fabricating the same, and more particularly, to a light emitting device, in which nanorods are disposed such that an active layer is exposed therethrough and quantum dots are distributed between respective nanorods, whereby light emission from the quantum dots may be increased due to energy generated from a Multiple Quantum Well (MQW) structure being is transmitted to the quantum dots, and a method of fabricating the same.
2. Discussion of the Background
A white lighting system typically includes a light emitting device, which emits ultraviolet rays or blue light, and a fluorescent material, which emits light having long wavelengths by absorbing a portion of the light that is emitted from the light emitting device. Here, the light emitting device contains gallium nitride (GaN), particularly aluminum indium gallium nitride (AlxInyGazN), as its primary ingredient. This white lighting system uses a light source having a single wavelength, and thus has the advantages of a very simple structure and inexpensive cost compared to other types of white lighting systems which use light sources having various wavelengths.
Quantum dots are a minuscule material that was recently developed. Quantum dots generate fluorescent light in a narrow wavelength range, and the light thus generated is stronger than that generated by typical fluorescent materials. Quantum dots are particles in which nanoscale II-IV group semiconductor particles form a core. With quantum dots, light may be emitted when an excited electron drops from the conduction band to the valence band.
Quantum dots are used to increase the light emission efficiency of a light emitting device through Förster Resonance Energy Transfer (FRET), in which energy generated from a Multiple Quantum Well (MQW) of the light emitting device is transferred to the quantum dots. An active layer may also be formed using a coupled quantum dot structure that is double-stacked in the MQW in order to increase light emission efficiency through strong carrier confinement.
However, when the FRET of quantum dots is used, a light emitting device of the related art generally has a film shape, and the distance between the quantum dots and the MQW should be maintained at 10 nm or less. In this case, the quantum dots are a mono-layer applied to is the surface of a film, and thus the density of the quantum dots used for FRET is low. Therefore, it is difficult to increase light emission efficiency.
Furthermore, in order to improve the quality of the portion of the film in which FRET occurs, reverse epitaxial growth is carried out, in which a p-semiconductor layer, such as p-GaN, is grown first, and then an n-semiconductor layer, such as n-GaN, is grown. In this case, the effect that FRET has on increased light emission efficiency is considerably decreased.
Moreover, in the light emitting device of the related art, it is difficult to realize the uniformity of quantum dots on the surface of nanorods, and only some quantum dots participate in emission, depending on the position of the MQW on the nanorods. Therefore, in general, it is difficult to increase the efficiency of the light emitting device.
The information disclosed in this Background of the Invention section is only for better understanding of the background of the invention, and should not be taken as an acknowledgment or any form of suggestion that this information forms a prior art that would already be known to a person skilled in the art.